Experimental study of dye removal from industrial wastewater by membrane technologies of reverse osmosis and nanofiltration

Currently, biological method has been utilized in the treatment of wastewater -containing synthetic dyes used bytextile industries in iraq. the present work was devoted to study the operating feasibility using reverse osmosis (ro)and nanofiltration (nf) membrane systems as an alternative treatment method of wastewater discharged from iraqitextile mills. acid red, reactive black and reactive blue dyes were selected, based on the usage rate in iraq. effects ofdye concentration, ph of solution, feed temperature, dissolved salts and operating pressure on permeate flux anddye rejection were studied. results at operating conditions of dye concentration = 65 mg/l, feed temperature = 39°cand pressure = 8 bar showed the final dye removal with ro membrane as 97.2%, 99.58% and 99.9% for acid red,reactive black and reactive blue dyes, respectively. with nf membrane, the final dye removal were as 93.77%, 95.67%,and 97% for red, black and blue dyes, respectively. the presence of salt (particularly nacl) in the dye solution resultedin a higher color removal with a permeate flux decline. it was confirmed that ph of solution had a positive impact ondye removal while feed temperature showed a different image. a comparison was made between the results of dyeremoval in biological and membrane methods. the results showed that membrane method had higher removalpotential with lower effective cost. the present study indicates that the use of nf membrane in dye removal from theeffluent of iraqi textile mills is promising.